International Humanitarian Law (IHL) is in a state of some turbulence, as a result of, among other things, non-international armed conflicts, terrorist threats and the rise of new technologies. This incisive book observes that while states appear to be reluctant to act as agents of change, informal methods of law-making are flourishing. Illustrating that not only courts, but various non-state actors, push for legal developments, this timely work offers an insight into the causes of this somewhat ambivalent state of IHL by focusing attention on both the legitimacy of law-making processes and the actors involved. Investigating what law-making processes reveal about the overall state of this legal regime, this thought-provoking book shows that current developments display a far-reaching disagreement about the direction into which IHL should evolve. It explores the most relevant trends in the development of IHL including the absence of formal law-making by states, informal law-making through manual processes and the increasing role of sub and non-state actors. Law-Making and Legitimacy in International Humanitarian Law will be of benefit to scholars and students of international law and relations, as well as practitioners working in the field of IHL, particularly in government ministries, international organizations and NGOs.